I use TP-LINK for several years but never heard of such a feature called "WLAN Client"...
What's the model number of your old TP-LINK?
What are you trying to fulfill with that feature?

Hi,

C2 has a mode named WDS bridge to use it as wireless client (+ AP)...

ok I'll give it a try.... I have a cable modem having 2.4 GHz and 5 GHz transmitter,and I have subscribed to 120 MBit bandwidth.
And I have 20 cm thick concrete walls between the modem and my IT lab so I want to get for sure 120 Mbit through the air and two doors between the living room and my lab.
With a gross bandwidth of about 750 Mbit this seems to be possible.
Anyway the older models just directly named it "Client" so I was really confused.

Edit:
I found the WDS function, but the TPlink thing called Archer C2 AC750 (and pls bother me with "upgrade the firmware", such things have to work out of the box) doesn't find the 5 GHz WLAN from my Technicolor cable modem.... and it doesn't see the 5 GHz network of my neighbour who is subscriber at the same company and has the same type of modem.

So maybe one cable modem can be defect but two not found that reveals a significant incompatibility. Therefore it found one FritzBox having 5 GHz enabled. So fine when it works with da Fritz box but not fine for me.

So I send it back and get refund...